The present disclosure relates to file transfer protocol (FTP). Computers can use FTP to communicate with each other over a network, such as the Internet. For example, an FTP session may be initiated between an FTP client computer and an FTP server computer. The FTP client computer can access directories, files, and other types of data stored on the FTP server. In some examples, the FTP client performs tasks that may include retrieving a directory listing from the FTP server, retrieving a file from the FTP server, sending a file to the FTP server, and/or modifying files stored on the FTP server computer. During different FTP sessions, an FTP client computer may need to communicate with different types of FTP server computers. For example, the FTP server computers may vary with respect to their operating systems, available connection modes, available data transfer modes, output language, output style, and/or authentication techniques.